1. Momentum and Impulse
SPH4U

2. Linear Momentum
Linear momentum is defined as the product of an object’s mass and its instantaneous velocity:

3. Linear Momentum
Linear momentum is defined as the product of an object’s mass and its instantaneous velocity: It is a vector quantity and has units of

4. Impulse
An unbalanced force acting on an object will cause an acceleration that will change its instantaneous velocity and therefore its momentum.

5. Impulse
An unbalanced force acting on an object will cause an acceleration that will change its instantaneous velocity and therefore its momentum. This change in momentum is called the impulse.

6. Momentum and Impulse: Example
A book of mass 1-kg falls on the floor and is stopped by the floor. Its speed just before impact was 5 m/s. What is the:
momentum of the book before impact?
momentum of the book after impact?
change in momentum (impulse)?

7. Momentum and Impulse: Example
A book of mass 1-kg falls on the floor and is stopped by the floor. Its speed just before impact was 5 m/s. What is the:
momentum of the book before impact?

8. Momentum and Impulse: Example
A book of mass 1-kg falls on the floor and is stopped by the floor. Its speed just before impact was 5 m/s. What is the:
momentum of the book before impact?

9. Momentum and Impulse: Example
A book of mass 1-kg falls on the floor and is stopped by the floor. Its speed just before impact was 5 m/s. What is the: (b) momentum of the book after impact?

10. Momentum and Impulse: Example
A book of mass 1-kg falls on the floor and is stopped by the floor. Its speed just before impact was 5 m/s. What is the: (b) momentum of the book after impact?

11. Momentum and Impulse: Example
A book of mass 1-kg falls on the floor and is stopped by the floor. Its speed just before impact was 5 m/s. What is the: (c) change in momentum (impulse)?

12. Momentum and Impulse: Example
A book of mass 1-kg falls on the floor and is stopped by the floor. Its speed just before impact was 5 m/s. What is the: (c) change in momentum (impulse)?

13. Momentum and Impulse: Example
A book of mass 1-kg falls on the floor and is stopped by the floor. Its speed just before impact was 5 m/s. What is the: (c) change in momentum (impulse)?

14. Momentum and Impulse: Example
A book of mass 1-kg falls on the floor and is stopped by the floor. Its speed just before impact was 5 m/s. What is the: (c) change in momentum (impulse)?

15. Newton’s 2nd Law

16. Newton’s 2nd Law

17. Newton’s 2nd Law

18. Newton’s 2nd Law

19. Force-time Graphs
Impulse is therefore the area under a force-time graph:

20. Force-time Graphs
Impulse is therefore the area under a force-time graph:
Same impulse

21. Force-time Graphs
Force-time graphs are most useful when the force is not constant:

22. Average Force
For such cases, we consider the average force, which is the force that if constant would give us an equal area over the same time interval.

23. Force-time Example
A 0.27-kg volleyball with an initial velocity of 2.7 m/s [E], hits a net, stops, and drops to the ground. The average force exerted on the volleyball by the net is 33 N [W]. How long is the ball in contact with the net?

24. Force-time Example
A 0.27-kg volleyball with an initial velocity of 2.7 m/s [E], hits a net, stops, and drops to the ground. The average force exerted on the volleyball by the net is 33 N [W]. How long is the ball in contact with the net?

25. Force-time Example
A 0.27-kg volleyball with an initial velocity of 2.7 m/s [E], hits a net, stops, and drops to the ground. The average force exerted on the volleyball by the net is 33 N [W]. How long is the ball in contact with the net?

26. Force-time Example

27. Force-time Example

28. Force-time Example

29. Force-time Example

30. More Practice
Textbook Questions
p. 238 #4, 10
p. 269 #9, 10, 7